It has been known in the metal finishing art to treat metal surfaces with various treatment layers, both to impart corrosion resistance and to provide pigmented coatings. U.S. Pat. Nos. 4,165,242; 5,385,655; and 5,603,818, for example, describe various pretreatment, coating and sealer compositions that impart corrosion resistance to metals. While virtually any metal is susceptible to corrosion, the problem can be particularly pronounced with small metal parts, such as nuts, bolts, screws, assemblies and other fasteners. These parts cannot be easily racked for treatment, and are therefore typically treated in bulk such as in a basket, on a conveyor line or in a barrel. Bulk treatment, however, can cause physical defects in the coating through contact points between the parts and by abrasion of the films due to reorientation, handling and transportation of the parts from one stage to the next. These defects invariably result in poor corrosion performance, with the coated parts showing significant rusting at the damaged sites within 48 hours of salt spray testing. These damaged sites are typically on, but not limited to, the sharpest edges of the parts, such as along a washer's edge, the crown of a bolt head and the outermost part of the bolt threads. Defects can also occur where the threads of one bolt cut into the film of another. This type of damage can occur anywhere in the coating, rinsing, unloading and/or curing processes. Process changes, formulation variations and coat-out parameters appear to have no significant role in correcting this problem.